From a006d4d1b6fd6d5136a96437048682063d3bd5c7 Mon Sep 17 00:00:00 2001
From: Helmut Januschka <helmut@januschka.com>
Date: Fri, 20 Mar 2026 08:56:09 +0100
Subject: [PATCH] perf: use direct gradient decode path in SingleGradientOnly

---
 jxl/src/frame/modular/decode/specialized_trees.rs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/jxl/src/frame/modular/decode/specialized_trees.rs b/jxl/src/frame/modular/decode/specialized_trees.rs
index dfe3bde37..e22bf427a 100644
--- a/jxl/src/frame/modular/decode/specialized_trees.rs
+++ b/jxl/src/frame/modular/decode/specialized_trees.rs
@@ -348,9 +348,13 @@ impl ModularChannelDecoder for SingleGradientOnly {
         br: &mut BitReader,
         histograms: &Histograms,
     ) -> i32 {
-        let pred = Predictor::Gradient.predict_one(prediction_data, 0);
+        let pred = clamped_gradient(
+            prediction_data.left as i64,
+            prediction_data.top as i64,
+            prediction_data.topleft as i64,
+        );
         let dec = reader.read_signed_clustered_inline(histograms, br, self.clustered_ctx);
-        make_pixel(dec, 1, pred)
+        dec.wrapping_add(pred as i32)
     }
 }